Re: [PATCH v3 0/8] RDMA: Enable operation with DMA debug enabled

Marek Szyprowski
2026-03-18T08:03:08Z

Hi Leon,

On 17.03.2026 20:05, Leon Romanovsky wrote:
> On Mon, Mar 16, 2026 at 09:06:44PM +0200, Leon Romanovsky wrote:
>> Add a new DMA_ATTR_REQUIRE_COHERENT attribute to the DMA API to mark
>> mappings that must run on a DMA‑coherent system. Such buffers cannot
>> use the SWIOTLB path, may overlap with CPU caches, and do not depend on
>> explicit cache flushing.
>>
>> Mappings using this attribute are rejected on systems where cache
>> side‑effects could lead to data corruption, and therefore do not need
>> the cache‑overlap debugging logic. This series also includes fixes for
>> DMA_ATTR_CPU_CACHE_CLEAN handling.
>> Thanks.
> <...>
>
>> ---
>> Leon Romanovsky (8):
>> dma-debug: Allow multiple invocations of overlapping entries
>> dma-mapping: handle DMA_ATTR_CPU_CACHE_CLEAN in trace output
>> dma-mapping: Clarify valid conditions for CPU cache line overlap
>> dma-mapping: Introduce DMA require coherency attribute
>> dma-direct: prevent SWIOTLB path when DMA_ATTR_REQUIRE_COHERENT is set
>> iommu/dma: add support for DMA_ATTR_REQUIRE_COHERENT attribute
>> RDMA/umem: Tell DMA mapping that UMEM requires coherency
>> mm/hmm: Indicate that HMM requires DMA coherency
>>
>> Documentation/core-api/dma-attributes.rst | 38 ++++++++++++++++++++++++-------
>> drivers/infiniband/core/umem.c | 5 ++--
>> drivers/iommu/dma-iommu.c | 21 +++++++++++++----
>> drivers/virtio/virtio_ring.c | 10 ++++----
>> include/linux/dma-mapping.h | 15 ++++++++----
>> include/trace/events/dma.h | 4 +++-
>> kernel/dma/debug.c | 9 ++++----
>> kernel/dma/direct.h | 7 +++---
>> kernel/dma/mapping.c | 6 +++++
>> mm/hmm.c | 4 ++--
>> 10 files changed, 86 insertions(+), 33 deletions(-)
> Marek,
>
> Despite the "RDMA ..." tag in the subject, the diffstat clearly shows that
> you are the appropriate person to take this patch.

I plan to take the first 2 patches to the dma-mapping-fixes branch
(v7.0-rc) and the next to dma-mapping-for-next. Should I also take the
RDMA and HMM patches, or do You want a stable branch for merging them
via respective subsystem trees?

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland